1. Technical Field
The invention relates to and more specifically to a semiconductor structure and more specifically to an electrostatic discharge protection circuit.
2. Description of the Related Art
Semiconductor devices are used in elements for many products such as MP3 players, digital cameras, computer, etc. As the application increases, the demand for the semiconductor device focuses on small size and large circuit density. In the semiconductor technology, the feature size has been reduced. In the meantime, the rate, the efficiency, the density and the cost per integrated circuit unit have been improved.
Recently, a power-saving IC is a trend for development for a semiconductor device. The power-saving IC usually uses a LDMOS or an EDMOS as a switch. For example, a method for increasing a breakdown voltage (BVdss) of a semiconductor device such as a LDMOS or an EDMOS is decreasing a dopant concentration of a drain region or increasing a drift length.
Electrostatic discharge (ESD) is a phenomenon of electrostatic charge transfer between different objects with the accumulation of the electrostatic charges. The ESD occurs for an extremely short period of time, which is only within the level of several nano-seconds (ns). A very high current is generated in the ESD event, and the value of the current is usually several amperes. Consequently, once the current generated by the ESD flows through a semiconductor device, the semiconductor device is usually damaged due to high power density. Thus, the ESD protection device has to provide a discharge path to prevent the semiconductor device from being damaged when the electrostatic charges are generated in the semiconductor device by machine or human body.